Mercruiser 4.3 Governor/Rev Limiter

[ChrisKatana]

4.3 Mercruiser in a 99 Sunesta.
@ WOT a noise comes from the engine, sounds like a vibration, (lasts for about 1 second) or a high speed wobble, the boat slows very slightly, then continues on, this vibration happens about every couple of seconds at wot.
It feels like it is hitting what seems to be rev limiter or speed limmiter.
Trim of the outdrive has no effect, so it's not speed related.
We have replaced the alternator and coil, new prop.
Problem did not exist with old prop, but it was damaged, missing part of a lobe and nicked up in gernal, and thus not reaching the current rpm, ~ 4500rpm.

Maybe unrelated but the tach is only reading about 1/2 the actual rpm
The engine runs fine, performs great but has this issue at WOT.

Thanks for your help,
Chris

 

[beermunk]

Re: Mercruiser 4.3 Governor/Rev Limiter

4.3 Mercruiser in a 99 Sunesta.
@ WOT a noise comes from the engine, sounds like a vibration, (lasts for about 1 second) or a high speed wobble, the boat slows very slightly, then continues on, this vibration happens about every couple of seconds at wot.
It feels like it is hitting what seems to be rev limiter or speed limmiter.
Trim of the outdrive has no effect, so it's not speed related.
We have replaced the alternator and coil, new prop.
Problem did not exist with old prop, but it was damaged, missing part of a lobe and nicked up in gernal, and thus not reaching the current rpm, ~ 4500rpm.

Maybe unrelated but the tach is only reading about 1/2 the actual rpm
The engine runs fine, performs great but has this issue at WOT.

Thanks for your help,
Chris

Check the runout on the prop shaft?

 

[ChrisKatana]

Re: Mercruiser 4.3 Governor/Rev Limiter

Check the runout on the prop shaft?

Is there an easy way to do this?
Can I just visually check for runout at the prop? or is this a more involved check?

 

[Bondo]

Re: Mercruiser 4.3 Governor/Rev Limiter

Is there an easy way to do this?
Can I just visually check for runout at the prop?

Ayuh,... Any detectable, aka. Visual wobble in the end of the propshaft is of Concern...
Hand turn it in neutral, motor off,+ have a Look...

and thus not reaching the current rpm, ~ 4500rpm.

That's alittle Low,... When was That,..?? What about Now,..??
Are the props the Same Size,..?? Manufacturer,+ Models,..??

My 1st WAGuess is, there's Crap in the fuel filters...